In a typical cellular wireless communication system, an area is divided geographically into a number of cell sites, each defined by a radio frequency (RF) radiation pattern from a respective base station. The base stations of the cells are then coupled to a switch or gateway (hereafter “switching system”) that provides connectivity with a transport network and/or to a signaling network. When a mobile station (i.e., wireless communication device), such as a cellular telephone, personal digital assistant, pager, or appropriately equipped portable computer, for instance, is positioned in a cell, the mobile station may then communicate via an RF air interface with the base station of the cell. Consequently, a communication path can be established between the mobile station and the network, via the air interface, the base station and the switching system. In this way, the base station(s) and switching system work in combination to function as a radio access network (RAN), providing mobile stations with RF access to engage in network communications, such as telephone calls or Internet communications.
In general, the air interface used for communications from a base station to mobile stations (i.e., the forward link) may be divided into a number of channels, including traffic channels used to carry bearer traffic (e.g., voice or other user data) and control channels used to carry overhead messages. Depending on the wireless technology used, the air interface can be divided into these channels through code division multiplexing (with each channel defined by modulation with a specific code), time division multiplexing (with each channel defined as a segment of time), frequency division multiplexing (with each channel defined by modulation with a specific frequency), and/or some other mechanism.
When a RAN receives a request to connect a call to a mobile station (which may be for various different types of communications, such as voice communications or data communications), the RAN will typically page the mobile station in an effort to determine whether the mobile station is available to receive the call. In practice, for instance, the switching system may direct the serving base station to broadcast over an air-interface paging channel, a general page message directed to the mobile station. If the mobile station receives the page message, the mobile station would then respond with an acknowledgment message back to the RAN, which would cause the switching system to continue setup of the call to the mobile station. On the other hand, if the RAN does not receive an acknowledgement from the mobile station within a set period of time, the RAN may then re-page the mobile station. Further, the RAN may repeat the re-paging process a set number of times or until the RAN receives an acknowledgement from the mobile station. Ultimately, if the RAN does not receive any page-acknowledgement from the mobile station, the RAN may programmatically conclude that the call setup paging process failed.
Furthermore, since mobile stations register with a RAN from time-to-time, it is possible that when a RAN pages a mobile station, the mobile station may have traveled out of the coverage area in which it last registered. As such, existing RANs may be configured for “intersystem” paging in order to page an access terminal that is no longer located in its last-registered coverage area. In particular, a RAN may be configured to send a page to a mobile station in its registered coverage area, which is served by a given switching system, as well as to send an “intersystem” page in a nearby coverage area that is served by another switching system. Thus, in the event the mobile station has moved into the coverage area served by the other switching system, the intersystem page should reach the mobile station.